France Activates Anti-Drone Jammers After Suspected Drone Overflight of Nuclear Submarine Base

French Military Uses Jammers After Suspected Drones Fly Over Ile Longue

French authorities deployed electronic jamming systems after several suspected drones were detected above the Ile Longue submarine base off the Brittany coast, prosecutors said on Friday as they opened a formal investigation into the incident.

Prosecutor Frédéric Teillet said the overflight occurred on Thursday evening. No drones were shot down and no operators have yet been identified. "No link with foreign interference has been established at this stage," he added, while noting investigators must still "confirm whether or not these were drones" and determine the exact type and number of devices.

A source close to the inquiry told AFP that five devices were detected above the base at around 18:30 GMT.

An anti-drone sweep and search operation was launched. The marine battalion responsible for protecting the facility "fired a jammer, not a firearm," Teillet clarified, describing the response as electronic countermeasures rather than kinetic action.

Ile Longue houses France's four ballistic missile submarines — Le Triomphant, Le Téméraire, Le Vigilant and Le Terrible — with at least one vessel typically at sea to maintain the country's continuous sea-based nuclear deterrent. France has kept a sea-based nuclear force since 1971; its submarines carry M51 strategic missiles capable of delivering multiple nuclear warheads.

Guillaume Le Rasle, spokesman for the maritime prefecture, told AFP that "sensitive infrastructure was not threatened," though he earlier said it was "too early to determine" the origin of the flights and suggested the sorties were "intended to cause concern among the population." He also noted that drone activity in the restricted Crozon peninsula area is not unprecedented.

Mysterious drone incursions over airports and sensitive sites have unsettled parts of Europe in recent months. With more than three years into Russia's invasion of Ukraine, officials have warned such disruptions could form part of hybrid-warfare tactics aimed at European countries backing Kyiv.

Defence Minister Catherine Vautrin told broadcaster TF1 that any overflight of a military base is prohibited in France. "A complaint has been filed, an investigation is underway, and it is this investigation that will determine what this overflight was all about," she said, praising the response of personnel on site.

The Ile Longue complex is a tightly guarded installation employing around 2,000 people, including roughly 1,500 civilians, and is protected by approximately 120 maritime police officers working alongside marines. Drone flights are prohibited over the Crozon peninsula to protect the military infrastructure located there.